Pitfalls of the Morphologic Approach

Abstract

To the Editor: In the October 2005 issue, Forman et al confirm the heterogeneity of lissencephaly (LIS) type I and suggest classifying it into 4 subtypes (LIS-4LP, LIS-4LA, LIS-3L, and LIS-2L) that they consider to be correlated with the underlying genetic defect. In addition, they reject the notion of a third group of LIS because of lack of migrational disorders observed in this group. Our extensive evaluation in fetal LIS prompts us to point out the pitfalls of a morphologic approach in the evaluation of LIS and led us to a new conceptual approach of classification based on the pathophysiological mechanisms. Lissencephaly is a descriptive term referring to absence/rarefaction of gyri and sulci. For neuropathologists, distinction between the 2 major groups of LIS, called LIS type I and LIS type II, is histologic. Classically, the so-called 4-layered cortex of …